On Wed, Jun 17, 2015 at 1:33 AM, Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx> wrote: > wake_futex_pi() wakes the task before releasing the hash bucket lock > (HB). The first thing the woken up task usually does is to acquire the > lock which requires the HB lock. On SMP Systems this leads to blocking > on the HB lock which is released by the owner shortly after. > This patch rearranges the unlock path by first releasing the HB lock and > then waking up the task. > > [bigeasy: redo ontop of lockless wake-queues] > Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> > Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx> > --- > * Davidlohr Bueso | 2015-06-16 12:50:26 [-0700]: > >>I prefer having two separate patches, thus keeping their own changelog >>for the change justification. > > okay, here it is on top of #1. A handful of boot test failures on ARM/OMAP were found by kernelci.org in next-20150619[1] and were bisected down to this patch, which hit next-20150619 in the form of commit 881bd58d6e9e (futex: Lower the lock contention on the HB lock during wake up). I confirmed that reverting that patch on top of next-20150619 gets things booting again for the affected platforms. I haven't debugged this any further, but full boot logs are available for the boot failures[2][3] and the linux-omap list and maintainer are Cc'd here to help investigate further if needed. Kevin [1] http://kernelci.org/boot/all/job/next/kernel/next-20150619/ [2] http://storage.kernelci.org/next/next-20150619/arm-multi_v7_defconfig/lab-khilman/boot-omap5-uevm.html [3] http://storage.kernelci.org/next/next-20150619/arm-omap2plus_defconfig/lab-tbaker/boot-omap3-beagle-xm.html -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in
